"As Above, So Below" director John Dowdle, left, and producer Drew Dowdle discuss the film, which they also wrote, at a Legendary Pictures panel at Comic-Con International in San Diego in July. (Richard Shotwell/Invision/AP)

Set in the catacombs beneath Paris, Legendary’s new horror film “As Above, So Below” sees a group of adventures, led by enterprising scholar Scarlett Marlowe (Perdita Weeks), set out to reclaim the mythic philosopher’s stone, a powerful alchemical artifact said to possess the ability to turn base metals into gold. But the expedition takes a surprising, and sinister, turn when Marlowe and her companions seemingly encounter horrors from their pasts, and possibly enter the gates of Hell.

The film is the latest project from the producing-directing team of Drew and John Dowdle, who most recently fashioned 2010’s “Devil,” a supernatural thriller about five strangers trapped in an elevator and the evil lurking among them.

But the pair has a history with horror — John, a New York University film school graduate, and Drew, a former mergers and acquisitions specialist on Wall Street, earned early attention with “The Poughkeepsie Tapes,” a hard-R-rated quasi-documentary about a serial killer’s cache of home movies, and ” Quarantine,” their 2008 remake of the popular Spanish horror film “[REC].” (Their next film, “The Coup,” a politically minded family survival tale tentatively set for release next year, will see them begin to move away from the genre somewhat.)

“As Above, So Below” director John Dowdle, left, and producer Drew Dowdle discuss the film, which they also wrote, at Comic-Con International in San Diego in July. (Richard Shotwell/Invision/AP)

Hero Complex recently caught up with the duo by phone to discuss the origins of “As Above, So Below,” which arrives in theaters Friday, the experience of shooting in Paris and finding a way to stay motivated while working in airless underground chambers for days on end.

Hero Complex: How did you hit upon this notion to set a found-footage horror movie in the Paris catacombs?

John: Drew and I had for years talked about, wouldn’t it be cool to do a female Indiana Jones movie that is in found footage, to do that kind of epic movie from a really intimate angle? We had also been really interested in the catacombs but had never really put the two together. We had a movie we were about to go make called “The Coup” that fell apart — thankfully we got to rebuild it and make it — we were like, “What are we going to do?” We got a call from [Legendary chief] Thomas Tull and he was like, “I’d love to do something in the Paris catacombs. Do you have any ideas?” A lightning bolt went off. We were like, that would be perfect for Scarlett Marlowe and we could put those two together and it all just fell into place.

Drew: We had this alchemical background for the character, and once we thought, “Well, if we set her in Paris…” With just a little bit of research we started realizing that Nicholas Flamel was such a touchstone of alchemy in Paris at that time … and all those dots started connecting that we might not have thought of if we hadn’t gotten that phone call.

HC: That’s a rather unusual way for a project to come together, is it not? To be contacted by a studio head with an idea?

John: It’s a little unusual. We’ve been friends of the court over at Legendary for years. We’ve circled around a number of different things with them. We’re part of Thomas’ stable of filmmakers that he calls. We’ve gone over to his house and watched movies. We’re all buds at this point.

Drew: And Thomas is a little different than most studio head types. He really is an idea machine. He’s constantly watching things on TV and then picking up the phone and calling his filmmaker friends and saying, “What have you got here? What have you got there?” He’s constantly trying to generate ideas internally with his filmmaker relationships. He’s a really fun guy to work with as a result.

HC: Did you already have a script involving this character that you then changed to include the catacombs angle? Or did you start from scratch?

John: We hadn’t actually started laying anything down. It was more like a character and sort of a rough idea without really a good place to go. We needed that thread you could pull and follow down some specific rabbit hole. We didn’t quite have that yet and frankly we’re doing 10 different things and weren’t totally focused on it at the time. It brought it from a background project to something right up in the foreground.

Drew: “The Coup,” it just didn’t fall apart, it fell apart the night before our flights to Thailand. It was less than 24 hours before we were leaving and the entire crew was in Thailand waiting for us. It fell apart in epically heartbreaking fashion. Then we got the call the next day from Thomas out of the blue. It was just one of those serendipitous moments were you say, “OK, I guess that’s what we should be doing now.” From that phone call to pre-production, it was about three months. It was incredibly fast. That was in November [2012], and we were on our location scout in March [2013].

John: We literally made two movies simultaneously. We went to Paris and shot “As Above” and did a really fast seven-week director’s cut for the studio, they loved it, we went to Thailand, shot “The Coup” and then came back and did post on both simultaneously. It was a crazy, exciting, fun year. I feel like the two projects helped each other. We learned a lot on both.

HC: Did you shoot all of “As Above” in Paris and how long were you there?

John: We shot the whole thing there. We were there I think a total of three and a half months. I think we shot six weeks, five of the weeks were underground.

HC: Was it difficult to get permission to shoot in the catacombs, or did you work primarily in areas that are generally accessible to the public?

Drew: It required a lot of patience and arm-twisting. There were a few locations that we really wanted that were the hardest to get permission. The public catacombs where all the bones are ornately laid out was one, and something called the Faust System, where they’re walking through water and where all the graffiti is, those two locations were really difficult. We actually went right up to the night before shooting before we had official permission on both of those locations.

John: The Faust System is actually illegal — you can get arrested for going in there. It’s kind of the medieval area of the catacombs and we got permission as long as we didn’t show exactly how to get in. It’s actually quite safe.

HC: What’s it like to work underground for such an extended period of time? I would imagine that that combined with the subject matter of what you’re shooting could become crazy-making.

John: We were in Paris in the spring and summer, and we were six stories underground in the dark 10 hours a day, five days a week. It starts to make you feel a little nuts. It’s kind of a nightmarish space down there. To spend day after day down there, it’s weird. There’s no light. The air doesn’t really move. It’s kind of moist and soggy; you hit your head on the ceiling a bunch.

Drew: You really notice it as the week wears on. It’s hard keeping everybody’s energy up in that space. It’s so dark and it’s so stagnant. The air quality is fine, but the air doesn’t move so the sound of voices, it’s all very strange. One of our bigger challenges was just trying to keep everybody energetic.

HC: Is it physically difficult to get in and out of there with all the equipment?

John: Very. One of the main areas we used is a section of the catacombs that was used by cloistered Capuchin monks in the 1600s. There were six stories of stairs going down, so we’d bring some equipment in that way. We tried to shoot as practically as possible because it just helps performances so much when you’re actually in the real space and no one’s stepping off set to call their buddies and see what they’re doing after the shoot. It kept everyone focused.

HC: “The Descent” used a cavern setting to great, claustrophobic effect. Were there specific films that you looked to before you began shooting that informed your approach to “As Above”?

John: A big one for us was “The Shining.” Stylistically it looks a lot different than that, but the sense of dread [was inspirational]. “Event Horizon,” we definitely watched that as a reference. “Flatliners.”

Drew: We used more thematic references than we used underground movies. Our hope on this movie was that it would be something more than just people trapped underground. That’s obviously a big part of it, the setting being the catacombs is a major part of the character of the movie, but we wanted it to be a little bigger thematically than just people trapped in the catacombs.

John: We sort of play the claustrophobia right up top. Usually in a movie like this you’d start wider and as the movie goes you’d go tighter and tighter and tighter [with the framing of the shots]. We were like, “Let’s play the claustrophobia right when they get underground and start to loosen it up.” By the end, they’re in quite big caverns and stuff but at that point the scares are more surreal in nature. It was fun building that arc. We did find one thing when shooting: If the camera is seeing the ceiling, there’s just a certain tension to everything. There’s something about having thousands of pounds of stone right over your head that is really unnerving. We tried to keep the ceiling in the shot as much as possible. That does something to you after a while.

Perdita Weeks and Ben Feldman in a scene from the film “As Above, So Below.” (Universal Pictures)

HC: In terms of assembling the cast, which includes “Mad Men” actor Ben Feldman, what qualities were you looking for?

John: We tried to find people who were very different from each other. For Scarlett specifically we actually read north of 300 people. We searched Los Angeles. We went to Paris to search there. We went to London also. We were looking in all three cities for quite some time and found her three weeks before production. She blew our minds. She’s going to have a huge future.

Drew: Once we got underground we depended on the actors quite a bit to be crew as well. I think we lit most of the movie underground with the actors’ headlamps and embraced the accidental nature of it. The head cameras were very often the actual actors filming from a helmet camera. We asked a lot of them beyond performance. We shot a lot of the movie and lit a lot of the movie with the cast.

HC: How did you find the experience of working in France overall? Do you feel that the setting really helps distinguish “As Above” from other found-footage-style thrillers?

John: Drew and I really love French cinema and French New Wave was a huge inspiration to us when we started getting into film — as it is to so many young filmmakers — but we really wanted to go to France and immerse ourselves. Drew and I were the Americans. We had an all-French crew. We learned to pantomime really well to get ideas across. To have the authenticity we wanted to have a very small crew so that we could shoot guerrilla-style in the real places. Paris is such a beautiful place, you could throw the camera out the back of a truck and whereever it landed would be just gorgeous.